Does the Rema say that? The Rema says they are chayiv in Seudah, and an intrinsic part of the Seudah is to drink (mashma that women are chayiv, but not bulletproof). If you have a specific mekor that women must drink, please share it with us.
However, I see no reason why women should be Patur. Why is it any different than the 4 Kosos? (Acc. to the Rema)